Leetcode078-subsets

Description

Given a set of distinct integers, nums, return all possible subsets (the power set).

Note: The solution set must not contain duplicate subsets.

Example

Input: nums = [1,2,3]
Output:
[
  [3],
  [1],
  [2],
  [1,2,3],
  [1,3],
  [2,3],
  [1,2],
  []
]

Solution

class Solution {
    public void backtrack(List<List<Integer>> res, List<Integer> temp, int[] nums, int start){
        res.add(new ArrayList<Integer>(temp));
        for (int i = start; i < nums.length; i++){
            temp.add(nums[i]);
            backtrack(res, temp, nums, i + 1);
            temp.remove(temp.size()-1);
        }
    }
    
    public List<List<Integer>> subsets(int[] nums) {
        List<List<Integer>> res = new ArrayList<>();
        backtrack(res, new ArrayList<Integer>(), nums, 0);      
        return res;
    }
}

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